<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
          "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
[
<!ENTITY pgprobackup     SYSTEM "pgprobackup.xml">
]>

<book id="pg-probackup">
  <reference>
   <title>pg_probackup Documentation</title>
&pgprobackup;
  </reference>
</book>